(1) Field of the Invention
The present invention relates to aminocyanopyridine compounds, and in particular, to tricyclic aminocyanopyridine compounds which inhibit mitogen-activated protein kinase-activated protein kinase-2 (MAPKAP-kinase 2, or MK-2), and compositions containing those aminocyanopyridine compounds.
(2) Description of the Related Art
Mitogen-activated protein kinases (MAPKs) are members of conserved signal transduction pathways that activate transcription factors, translation factors and other target molecules in response to a variety of extracellular signals. MAPKs are activated by phosphorylation at a dual phosphorylation motif with the sequence Thr-X-Tyr by mitogen-activated protein kinase kinases (MAPKKs). In higher eukaryotes, the physiological role of MAPK signaling has been correlated with cellular events such as proliferation, oncogenesis, development and differentiation. Accordingly, the ability to regulate signal transduction via these pathways could lead to the development of treatments and preventive therapies for human diseases associated with MAPK signaling, such as inflammatory diseases, autoimmune diseases and cancer.
In mammalian cells, three parallel MAPK pathways have been described. The best characterized pathway leads to the activation of the extracellular-signal-regulated kinase (ERK). Less well understood are the signal transduction pathways leading to the activation of the cJun N-terminal kinase (JNK) and the p38 MAPK. See, e.g., Davis, Trends Biochem. Sci. 19:470-473 (1994); Cano, et al., Trends Biochem. Sci. 20:117-122(1995).
The p38 MAPK pathway is potentially activated by a wide variety of stresses and cellular insults. These stresses and cellular insults include heat shock, UV irradiation, inflammatory cytokines (such as TNF and IL-1), tunicamycin, chemotherapeutic drugs (i.e., cisplatinum), anisomycin, sorbitol/hyperosmolarity, gamma irradiation, sodium arsenite, and ischaemia. See, Ono, K., et al, Cellular Signalling 12, 1-13 (2000). Activation of the p38 pathway is involved in (1) production of proinflammatory cytokines, such as TNF-α; (2) induction of enzymes, such as Cox-2; (3) expression of an intracellular enzyme, such as iNOS, which plays an important role in the regulation of oxidation; (4) induction of adherent proteins, such as VCAM-1 and many other inflammatory-related molecules. Furthermore, the p38 pathway functions as a regulator in the proliferation and differentiation of cells of the immune system. See, Ono, K., et al., Id. at 7.
The p38 kinase is an upstream kinase of mitogen-activated protein kinase-activated protein kinase-2 (MAPKAP kinase-2 or MK-2). (See, Freshney, N. W., et al., J. Cell, 78:1039-1049 (1994)). MK-2 is a protein that appears to be predominantly regulated by p38 in cells. Indeed, MK-2 was the first substrate of p38α to be identified. For example, in vitro phosphorylation of MK-2 by p38α activates MK-2. The substrates that MK-2 acts upon, in turn, include heat shock protein 27, lymphocyte-specific protein 1 (LAP1), cAMP response element-binding protein (CREB), ATF1, serum response factor (SRF), and tyrosine hydroxylase. The substrate of MK-2 that has been best characterized is small heat shock protein 27 (hsp27).
The role of the p38 pathway in inflammatory-related diseases has been studied in several animal models. The pyridinyl imidazole compound SB203580 has been shown to be a specific inhibitor of p38 in vivo, and also has been shown to inhibit activation of MK-2, (See, Rouse, J., et al, Cell, 78:1027-1037 (1994); Cuenda, A., et al, Biochem. J., 333:11-15 (1998)), as well as a MAP kinase homologue termed reactivating kinase (RK). (See, Cuenda, A., et al., FEBS Lett., 364(2):229-233 (1995)). Inhibition of p38 by SB203580 can reduce mortality in a murine model of endotoxin-induced shock and inhibit the development of mouse collagen-induced arthritis and rat adjuvant arthritis. See, e.g., Badger, A. M., et al., J. Pharmacol Exp. Ther., 279:1453-1461 (1996). Another p38 inhibitor that has been utilized in an animal model that is believed to be more potent than SB203580 in its inhibitory effect on p38 is SB 220025. A recent animal study has demonstrated that SB 220025 caused a significant dose-dependent decrease in vascular density of granulomas in laboratory rats. (See Jackson, J. R., et al, J. Pharmacol. Exp. Ther., 284:687-692 (1998)). The results of these animal studies indicated that p38, or the components of the p38 pathway, can be useful therapeutic targets for the prevention or treatment of inflammatory disease.
Due to its integral role in the p38 signaling pathway, MK-2 has been used as a monitor for measuring the level of activation in the pathway. Because of its downstream location in the pathway, relative to p38, MK-2 has been measured as a more convenient, albeit indirect, method of assessing p38 activation. However, so far, research efforts exploring therapeutic strategies associated with the modulation of this pathway have focused mainly on the inhibition of p38 kinase.
Several compounds that inhibit the activity of p38 kinase have been described in U.S. Pat. Nos. 6,046,208, 6,251,914, and 6,335,340. These compounds have been suggested to be useful for the treatment of CSBP/RK/p38 kinase mediated disease. Commercial efforts to apply p38 inhibitors have centered around two p38 inhibitors, the pyridinylimidazole inhibitor SKF 86002, and the 2,4,5 triaryl imidazole inhibitor SB203580. See, Lee, J. C., et al, Immunopharmacology 47, 185-192 (2000). Compounds possessing a similar structure have also been investigated as potential p38 inhibitors. Indeed, p38 MSP kinase's role in various disease states has been elucidated through the use of inhibitors.
Kotlyarov, A. et al, in Nat. Cell Biol., 1(2):94-97 (1999) introduced a targeted mutation into a mouse MK-2 gene, resulting in MK-2-deficient mice. It was shown that mice lacking MK-2 possessed increased stress resistance and survived LPS-induced endotoxic shock better than MK-2+ mice. The authors concluded that MK-2 was an essential component in the inflammatory response that regulates biosynthesis of TNFα at a post-transcriptional level. More recently, Lehner, M. D., et al, in J. Immunol., 168(9):4667-4673 (2002), reported that MK-2-deficient mice showed increased susceptibility to Listeria monocytogenes infection, and concluded that MK-2 had an essential role in host defense against intracellular bacteria, probably via regulation of TNF and IFN-gamma production required for activation of antibacterial effector mechanisms.
The location of MK-2 in the p38 signaling pathway at a point that is downstream of p38 offers the potential that MK-2 could act as a focal point for modulating the pathway without affecting as many substrates as would the regulation of an enzyme further upstream in the signaling cascade—such as p38 MAP kinase.
Accordingly, it would be useful to provide compounds that could serve to modulate the activity of MK-2—in particular, to act as inhibitors of MK-2 activity. It would be useful to provide a method of making such aminocyanopyridine compounds which was simple and straightforward. It would be even more useful if such method could be formulated as a “single pot” method, wherein all reactions that are required for the production of a tricyclic aminocyanopyridine MK-2 inhibitor can be carried out in a single vessel without removal or transfer of the contents to a separate vessel at some point during the production process.